Abstract: A mine roof support assembly which has a stowage or goaf screen lining pivoted to a floor-engaging sill structure and a piston and cylinder unit arranged between the sill structure and the screen to effect pivoting of the screen. A roof bar is pivotably connected to a bell-crank lever which is itself pivoted to the screen and a stiff rod is pivotably connected to the bell-crank lever and to the sill structure. The rod and bell-crank lever form a control linkage which exerts a compensating effect on the roof bar as the screen is pivoted to move the bar against or away from the roof, so that the bar maintains in horizontal orientation while the front end of the bar moves along a vertical line.